Assessment of Mass-Transfer Effects during Polyether Production from 1,3-Propanediol

A mathematical model is developed to simulate condensation polymerization of 1,3-propanediol to produce polytrimethylene glycol (PO3G) polyether. The model includes improved mass-transfer expressions that account for nonzero concentrations of water and monomer inside nitrogen bubbles and for increasing overall bubble surface area due to increases in bubble residence time. An objective function that accounts for the mole fractions of evaporated monomer, water and propanal is considered for parameter estimation. Improvements in the predicted monomer and water concentrations in the polymer and evaporation rates of monomer and water can be observed compared to a previous model.5, 6 However, predictions of degree of polymerization do not improve noticeably. Recommendations including revisions of the chemical mechanism to include additional reactions and accounting for evaporation of linear and cyclic oligomers in future models are suggested.